According to a known technology, a navigation apparatus for computing and displaying an appropriate guiding route to a destination successively acquires traffic information about roads such as congestion, accident, and highway regulation using VICS (Vehicle Information Communications System in Japan), RDS-TMC and the like. The navigation apparatus dynamically changes the guiding route to the destination in accordance with the acquired information.
According to the above-mentioned technology, the navigation apparatus described in a Japanese Patent Document JP-A-H11-37784 responds to a change in the guiding route and uses a screen to simultaneously display both the old guiding route before the change and a new guiding route after the change. By using such technology, a user can clearly understand a change from the old guiding route to the new one.
Using the technology described in the above patent document (JP-A-H11-37784), however, the user cannot comprehend the reason for the change from the old guiding route to the new one. The present invention has been made in consideration of the foregoing. It is therefore an object of the present invention to provide a navigation apparatus that dynamically changes a guiding route to a destination in accordance with information about traffic events on roads and allows a user to comprehend a reason for changing the guiding route.